This invention relates to a Virtual Design System that uses a mathematical 3D model of a real world object, performs an application of a design on that model, and which can be combined with an Optical Projection System to visualize the design and/or design data on the real world object.
Standard 3D-CAD (Computer Aided Design) systems are at present widely used or the realization and visualization of designs on objects. This includes the representation of an object from different perspectives, change of light sources, shadowing, rendering, animation, and related features. These standard systems represent a real world object internally as a mathematical model, which incorporates the three-dimensional data of the object in form of primitives such as lines, polygons and solid bodies, and an instruction set of the operations which can be performed to manipulate the data. Application of designs on 3D objects with help of these systems is done in the form of rendering techniques. Bitmap patterns are projected on the 3D-object for visualization purposes only, this is called texture mapping. For example, a fashion design is evaluated visually by trying out different textures and color combinations on different parts of the design.
With the presently available methods, there are three main difficulties:
1. Usually, the design is done in a pure 2D environment. The consequence is that inconsistencies, such as unexpected perspective views and genera unaesthetic effects, do not appear until the design has been applied to a real 3D object Such late findings can be very costly.
2. The application of a design onto a real 3D object is a tedious, messy, error-prone, unreproducable and time-consuming process. The decoration lines, masks and templates are positioned either in a complicated manual process, or with large inaccuracies due to individual differences in aesthetic perceptions.
3. The application of designs on virtual 3D objects using CAD software with texture mapping techniques provides a visualization of the designed 3D object, but does not provide accurate data for the application of the design on the real world object. The consequences are then as in point 2.
The present method is intended to give an artist or designer the possibility of applying designs onto 3D objects imported from CAD systems in form of surface or solid models and generate data that will be shared by production (meaning here the actual application of the 3D design onto the real object by means of an Optical Projection System, such work being for example: the application of templates. bands, ribbons and other decorating aid that is applied prior to painting or decorating an object, or simply the visualization of the design outline on the real object), engineering (providing the possibility to give instant feedback to the providers of the CAD model or the technical designers) and marketing or sales (for example for the presentation of the decorated CAD model to a customer, or for the generation of a computer animation). The subject matters of the document U.S. Pat. No. 5,490,080 are a method and a device for decorating a tridimensional object wherein a computer visualizes in advance the expected result. This method has the disadvantage that applications of designs on non-flat surfaces often lead to unacceptable distortions of the designs. Such findings often occur at a late stage when the real object has already been decorated, leading to costly re-work or even redesigning from scratch.
Contrary to traditional methods, in the present patent application, the complete design process occurs in a 3D Virtual Design Environment using a special 3D-CAD system. The production of a 3D decoration can then be tested virtually, avoiding inconsistencies and errors. And contrary to some previous design processes that use the 3D capabilities of computers, not only the visualization data, but also the exact data of the design applied onto the 3D object is used for the design process. The exact 3D data of the design work is used subsequently by an optical projection system. In the present patent application, the optical projection is done with a Laser Projection System or other Optical Projection Systems. An improved Laser Projection System is presented, previous proposals of such systems are described in US. Pat. Nos. 5,341,183, or 5,388,318. The Optical Projection System allows the visualization, now on the real world object, of the results obtained by the virtual design application using the CAD system. Further on, in the present invention, additional data gained from the 3D-CAD system during the design process can be used in manufacturing. measurement and alignment processes. As an example, object details and material characteristics can be incorporated
More specifically, the object of the present invention is to allow rapid correction of errors such as unwanted geometric distortions and to avoid projection occlusions.
This object is solved by a method of generating a design according to claim 1.
Further embodiments are disclosed in the subclaims. into the computer aided design process, imposing constraints on the design and assisting the designer during the application of the design on the real world object (e.g. constraints on the design due to the position of doors, windows, pilots, antennas, etc. on the real object).
Note regarding nomenclature:
The term projection is used here for two different situations:
A) When denoting the 2D to 3D projection done by the artist when designing using the Virtual Design Environment of the computer.
B) When denoting the process of the physical projection e.g. of the optical light beam (laser or other) onto the real 3D object, using the Optical Projection System.
Similarly, the term 3D object is referred to in two different situations:
A) When denoting the virtual, or 3D-CAD object
B) When denoting the real, physical object
One embodiment of the method consists of the following steps:
If a 3D CAD model exists:
The designer initially starts with a two dimensional image of the design which he wants to apply on an object. This 2D design is incorporated into a CAD system which possesses an internal 3D model of the mentioned object. The 2D draft is then projected onto the 3D model by using one of several methods available, in order to be able to visualize the decorated 3D model of the 3D object. This provides a possibility to evaluate the decorated 3D model before applying the design on a real world object. The virtual design environment allows for an overall improved design production. The reasons for the improvements are manifold. Applications of designs on non-flat surfaces often lead to unacceptable distortions of the design. Such findings often occur at a late stage when the real object has already been decorated, leading to costly re-work or even redesigning from scratch. In this method, the visualization of the 3D object with the incorporated design allows a better evaluation of the design at an early stage, and changes can be made as often as required at no extra cost. If the result is not satisfactory, the 3D decoration is redone by modifying the 2D decoration with subsequent repetition of the 2D onto 3D projection step. This loop is repeated until the result fulfills the requirements, such as, for example, that an insignia must be clearly discernible from certain viewing angles, or simply, that the design fulfills proposed aesthetical considerations.
Once approved, the decorated 3D model of the Virtual Design Environment becomes the new centerpiece of object definition from which:
A) Engineering can receive feedback and incorporate the decorated object back into engineering""s database. If necessary, they can modify the original 3D object using motivations provided by the virtual design application.
B) Production or manufacturing will be able to apply the exact decorations and other design data onto the real 3D object by using an Optical Projection System in conjunction with the data generated by the Virtual Design Environment with 100% repeatability.
C) Marketing/sales will be able to generate replica-exact computer-animations and presentations of the decorated 3D object, again using the data generated by the design environment.
The task of applying the decoration onto the real world object is done with the assistance of Optical Projection Systems, such as a 3D-Laser projector, as described below.
If a 3D-CAD model (either without design or with the design incorporated) does not exist:
The following cases are covered by using a special teaching (or digitizing function available for the vector scanning Laser system (prior art):
A) The 2D design is realized and applied to the object in the traditional way, (i.e. using templates, measuring aid, etc.) and after the 3D real object has been decorated, a two-projector Laser system is used to digitize (or teach-in) the approved design, e.g. using a known method of triangulation, thus providing data for reproducible subsequent object decorations.
B) The 3D decorated object already exists and the same design has to be reproduced on other objects, but no 3D CAD data of the object exists. Then again, a two-projector Laser system can be used as in A).
C) The 3D decorated object exists, for which a 3D CAD model exists, but no 3D decorated CAD model exists. In this case the two-projector Laser system is used to incorporate the design data and make it available for the computer. Then, the incorporated design data can be manipulated and modified in the virtual environment as described previously. Afterwards. the design can be applied again onto real objects.
The decorative 3D design done on a virtual 3D object using the Virtual Design Environment generates the data fed to the Laser System that will project the outlines (the line-artwork) accurately onto the real 3D object, in a fashion similar to Laser shows used for entertainment. The main difference to Laser shows is that with the present method, the laser projection is accurate on a 3D object, regardless of the relative position of the laser system. The Virtual Design Environment generates exact data of the design in real 3D coordinates. Typical accuracies are in the range of a couple of millimeters over object sizes of 20 m, or half a centimeter over 50 m objects.
For the projection of the 3D-design data onto the real world object prior art Laser Systems can be utilized. Additionally, a Laser System with a number of improvements can be utilized. The improvements are presented in this patent application. The features of the improved Laser System include:
1) Linewidth-control: a built-in device can dynamically vary the focussing. This feature can be used when projecting (scanning) over varying angles of incidence onto the surface or over varying distances to the object. In the first case, the change of the Laser beam spot size as a function of angle of incidence can be influenced to a certain decree, in the second case, the focussing is changed so as to guarantee a constant spot size over varying distances to the object within a scanned contour line. Contrary to prior art Laser Projection Systems available for the type of tasks we propose. linewidth control as a function of object properties is possible due to the information available from the Virtual Design Environment.
2) Laser class 3A: The software computes the distance to the object, and automatically modulates the Laser power in such a way that, in combination with the prior-art modulation as a function of scanning speed, a modulation as a function of the distance to the object is done, considering the change in beam diameter and the change in scanning speed as a function of the distance. Again, modulation of the Laser power as a function of the object distance properties is only possible due to the information available from the Virtual Design Environment.
3) Manual calibrations: for applications where a high accuracy is not required, or where periodic visual checking of reference points is enough, e.g., for positioning of templates, a lower cost Laser system can be used. Such a lower cost Laser system uses the same 3D projection software as the prior art Laser system, but there are no detectors or retroreflectors or detection circuits for the Laser calibration present; instead, the calibration points are targeted individually and manually using a trackball, mouse or joystick, and checked visually for accuracy. In this way, no detection circuitry is needed any more. (Prior art Laser systems use opto-electronic detection of points of reference which are used for calibration of the Laser systems to calculate their positioning relative to the 3D object. These reference points are attached to known positions on the 3D object.)